Large hydraulic turbine shafts include a thrust flange that is carried on and must rotate around on a supporting collar having thrust bearings positioned on the supporting collar and that carry most or all of the weight of the turbine shaft. The wear surface on a thrust bearing is subject to large stresses under extreme conditions. This thrust flange rotates on the surface of a thrust bearing wear pad. Conventionally, a wear surface on the thrust bearing wear pad is coated with a lubricant that separates the thrust bearing wear pad from the flange surface of the shaft. However, even minor impurities or foreign material that may accidentally mix into the lubricant can create significant damage on the face of the thrust bearing wear pad and cause it to wear unevenly. The unevenness in wearing can create significant problems overall in the operation of the shaft over time. Other duty conditions including heat and vibration can also have a detrimental effect on the smooth surface of a wear pad.
Thrust bearing wear pads have historically been formed of monolithic materials. A hundred years ago, these pads included single, solid wood pads. More recently, sophisticated polymers and composites have been deployed as the wear pads. These polymer and composite materials, however, have been found to be not sufficiently durable. Furthermore, the older single-piece solid wood pads that have been relatively successful in operation are increasingly difficult and expensive to source.